High sensitivity photodetectors and photon counters with a resolution at the photon level are useful in many civilian and military applications, including quantum cryptography, imaging at low levels of ambient illumination, light detection and ranging (LIDAR), space exploration, and medical imaging. Examples of highly sensitive photodetectors include photomultiplier tubes (PMTs), avalanche photodiodes (APDs), and quantum dot single-photon detectors (QDSPD). Nanomaterials, such as lead sulfide colloidal quantum dots, cadmium selenide colloidal nano-particles, and zinc oxide (ZnO) nano-particles and nanowires, have been used in the photodetectors.